Radiotherapy consists of projecting onto a predetermined region of a patient's body, a radiation beam so as to destroy or eliminate tumors existing therein. Such treatment is usually carried out periodically and repeatedly. At each medical intervention, the radiation source must be positioned with respect to the patient in order to irradiate the selected region with the highest possible accuracy to avoid radiating adjacent tissue on which radiation beams would be harmful. If movement of a patient is detected during treatment, the treatment should be halted to avoid irradiating areas of a patient other than a tumor location.
For this reason a number of monitoring systems for assisting the positioning of patients during radiotherapy and detecting patient movement have therefore been proposed such as those described in Vision RT's earlier patents and patent applications U.S. Pat. No. 7,889,906, U.S. Pat. No. 7,348,974, U.S. Pat. No. 8,135,201, U.S. Pat. No. 9,028,422, US2015/0265852, and WO2015/008040 (now pending as U.S. Ser. No. 14/899,112) all of which are hereby incorporated by reference.
In the systems described in Vision RT's patent applications, stereoscopic images of a patient are obtained and processed to generate data identifying 3D positions of a large number of points corresponding to points on the surface of an imaged patient. Such data can be compared with data generated on a previous occasion and used to position a patient in a consistent manner or provide a warning when a patient moves out of position. Typically such a comparison involves undertaking Procrustes analysis to determine a transformation which minimizes the differences in position between points on the surface of a patient identified by data generated based on live images and points on the surface of a patient identified by data generated on a previous occasion.
Treatment plans for the application of radiotherapy are becoming increasingly complex with treatment apparatus having multiple or floating iso-centers. Also, there is an increasing trend to make use of higher doses of radiation during treatment in order to reduce overall treatment time. Such increasing complexity and higher dosages bring with them the increasing possibility of mistreatment. With the increasingly complex treatment plans, in addition to identifying the location and dosage of radiation at the surface of the patient, it would be desirable to identify the internal locations where radiation is applied and to obtain feedback on the radiation dosages applied internally during the course of treatment.